New Copper Alloys

Copper Applications in Innovative Technology

By Robert Solbach

Introduction

The CDA Standards Advisory Group has the responsibility for administering and maintaining the "Unified Numbering System" in North America for all copper and copper alloys. The system is internationally recognized. The designation system is not, however, to be construed as specifications. Registration numbers are assigned to distinct compositions based on requests submitted to the Group. Anyone may submit a request for consideration. The compositions must be complete, analyzable for as registered, and in (or proposed) commercial use. They must also be non-proprietary, or licensable and in the public domain.

The Standards Advisory Group normally meets in New York in August at CDA headquarters and in December, in conjunction with the CDA Annual meeting. Consideration is given to all submittals at that time. It is expected that submittals be accompanied with appropriate physical and mechanical data sheets. All information keyed to the registration number, is entered into the CDA database and made available upon request. At some point in the near future, the database will be available on the Internet.

New compositions are driven by the need for improved performance, and are undoubtedly accompanied with cost effectiveness considerations. The technical difference in the alloys relating to their selection for an application is always based on a combination of their attributes. A designer's dilemma is in the compromise of balancing the attributes. In choice of a wire conductor material, electrical and thermal conductivity are paramount, but strength must also be considered. In the case of a conducting connector material in an automotive application, electrical conductivity is significant but strength and thermal fatigue are more significant, and resistance to elevated temperature stress relaxation weighs heavily in the selection equation. The drive to eliminate the possibility of lead contamination in potable drinking water has resulted in the registration of a series of new lead free, bismuth containing casting alloys. Naturally each new alloy is developed directed at a particular application. CDA's objective is to encourage and facilitate development of all copper alloys without regard to their intended commercial application, and to rationalize their identification.

A significant number of new alloys were registered in 1997. Several requested revisions to previously registered alloys were also acted on. The various designations and compositions are noted below. A few notes on capability and use have been included.

New Alloys Registered in 1997

The new copper beryllium alloys C17450 and C17460 in the mill hardened flat product form are for electrical conducting springs, contacts, and connectors, lead frames, diaphragms, and bellows. In rod form indicated applications are die cast plunger tips, sleeve bearings, plastic molding tooling, and resistance welding electrodes.

Alloy C19025 is intended for use in IC and transistor lead frames and electrical connectors. It has an electrical conductivity of 40 % IACS and a nominal UTS of 70 ksi. As noted in the data sheets accompanying it's registration request, it is shown as being available in three cold rolled tempers, H02, H04, and H06. Alloy C19710 has an electrical conductivity of 70%, is available as cold rolled and stress relieved in the HR04 and HR10 tempers. It is directed at the electrical terminal, springs, and lead frame area of application.

The new tin brass alloys C40810, C40850, C40860, and C42520 are flat products available in the annealed and five to six cold rolled tempers. Their areas of proposed application are automotive terminals, electronic connectors, lead frames and contact springs. The new phos bronze alloys C50780, C51080, C51180, C51980, and C52180 are also flat products available in the annealed and five to six cold rolled tempers, and are directed at the same areas of application.

C64725 is used for electrical springs, connectors and terminals for strength and resistance to stress relaxation.

C64740 is a new alloy intended use is in the IC semiconductor, lead frame area where corrosion resistance and formability are requisites.

C66300 is a new flat product alloy directed at the electrical and electronic connector applications in 5 rolled tempers from H04 to H14, three cold rolled and stabilized tempers, HR04, HR08, HR10 one O82, annealed temper. Generically it is considered an alternative to C51100.

The support mechanical and physical data for alloy C70250 have now been completed, and included in the database. It is an age hardened copper-nickel alloy in three tempers designed to meet the electrical and thermal conductivity, and stress relaxation requirements of the interconnection industry. Noted application areas are automotive and electrical connectors, semiconductor leadframes, and sockets.

Two UNS numbers were assigned to welding filler metal rod alloys. The Naval Sea Systems Command (NAVSEA) is interested in eliminating military specifications. A new ASTM document is in preparation to replace MIL-C-24679 on Copper-Nickel Alloy Forgings and Forging Stock. C70620 and C71520 are the military, restricted welding rod compositions, for 90-10 and 70-30 Cu Ni type alloys (respectively) which will be specified in the new ASTM document, for use on the C70600 and C71500 forgings.

The bismuth casting alloys which had received preliminary assigned UNS # C89325, C89831, C89833, C89835, and C89837 have temporarily been placed in an inactive status, but are commercially available in this case.

C92220 is a cast bronze grave marker alloy requested by the American Foundrymen's Society for the Department of Veterans Affairs (DVA). DVA is rewriting a specification for grave markers and has specified this alloy for the application. It is similar to, but different enough to require a unique UNS number based on the volume of U. S. Government specified grave markers.

The request for UNS alloy number assignments to be made for composite welding filler metals was not acted upon. Only solid filler metal, one composition, can be assigned a UNS number, by definition of the system.

New Alloy Compositions

Alloy Revisions

The composition change in alloy C15100 was made to reconcile the difference between that stated in ASTM B747 and that CDA Standard Designation list. The cobalt range in alloy C17530, a high electrical conductivity copper-beryllium alloy was removed in that it is a residual in the nickel range. The data sheets for alloy C36000 are being revised and updated. It is intended that they be available later this year. The casting alloy C89520 was adjusted based on alloy development studies conducted at CANMET in Ottawa, Ontario, Canada. Further physical and mechanical data are expected.

Alloy Reactivated

Alloy C66900 was moved from the inactive to the active list. Alloys that are no longer commercially available are moved to the Inactive List.

Revised and Reactivated Alloy Compositions

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